Tuesday, 12 December 2017

The sum of all parts of the quarry (2): finches

This December, the two roost counts at Berengrave are going to be rather far apart. First half of month was nice and early but, thanks to an operation, second half count will be nice and late. In the meantime, a chance to muse on what else, in addition to all those Magpies and Woodpigeon I keep going on about, gets counted. Yup, OCD muppet that I am, I try to count everything.

Results? All 'normal', but all fascinating, and helping to refine my personal views on the local populations.

How the reserve was promoted 32 years ago. Now? No school visits,
no fieldwork- mind you, no Borough Council, no Police Station.

The Finches
Still a close-your-eyes-and-you're-back-there species for me; Berengrave, 1986, more than 200 coming into roost at the southern end around the chalk washing ponds. Snow everywhere, flurries coming down, calling to the left, right and centre of me. Birds staring back at me through the gloom. Wonderful.

Of course, those cold winters were the exception rather than a norm even back then and, although locals always go on about how the regular roosts there have disappeared, were they ever regular?

Certainly a struggle nowadays, in line with sightings for much of the western half of the southern shore- slightly higher around the remaining orchards in the east of the estuary, but a double figure at roost would be something to celebrate. Of course, I now count from the south-west corner of the quarry, so far I've been able to resist checking numbers from the ground in the north-east.

Those early years of birding (I didn't start until in my twenties) had hundreds of Chaffinch roosting at the southern end of the pit. Today, birds still favour that end, and many arrive from the north and west; a scan of the treeline in the last half-hour of daylight will find numbers perched out, advertising the roost; in the minutes before sunset, they all drop in together; few are late to roost. Small numbers arrive from the south and west of the viewpoint; there are, of course, other local roost sites for townie finks.

The general trend is for fair numbers pre- year-end being followed by a peak at the start of the winter; mid-winters influxes have not been seen the past four winters. By February numbers are dropping off- dead, driven on by weather/food shortages, or when mild, perhaps even heading back toward the continent; by early March it seems to be just a few, most likely local breeders, left.

All highly irregular. Even in the better years they lead any observer a merry dance, jingling in to the quarry only to jingle out ten minutes later. The deep dip in mid-winter perhaps reflects onward passage during the coldest part of the year. One species for me to watch in the coming years.

Sadly, I have no recollection of a Greenfinch roost from all those years ago. I have yet to look up roost preferences (got to save some things for the years to come) and can only presume this reflects the population crash in recent years (what, BTO? No 'Birdtrends' webpage for Grefi? I was looking to make a link to there..) Based on ringing, we never see many into the UK each year so that 'monster' count of 16 this autumn may not actually be reflecting passage birds. The biggest hope for local trends is a slow year-on-year increase in numbers. Another good reason to keep dragging myself down twice a month 13 times a year..

Finally for the common finches (a species only gets a chart when I've seen it a dozen times to date)
a species that I remember more from the springs than the autumns. A trend not seen now, but as this is an irregular irrupter, why should they? The habitat is just not right, even though they (and Lesser Redpolls) used to like the north-east corner in the days before the birches and alders were routinely removed.

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